Reenforced paper and method of forming same



April 6, 1937. F. w. HUMPHNER I REENFORCED fAPER AND METHOD OF FORMING SAME Filed Nov. 29, 1935 myiw Patented Apr. 6, 1937 REENFORCED PAPER AND METHOD or FORMING SAME Ferdinand W. Humphner, Oak Park, 111., Minor to Mid-States Gummed Paper 00., a corporation of Illinois Chicago, 11L,

Application November 29, 1935, Serial No. 52.266

2 Claims.

This invention relates to reenforced paper and the method of forming the same. The invention is particularly useful in the forming of paper strips, tape, etc., adapted for use in sealing card- 5 board boxes, etc.

An object of the invention is to provide a composite paper strip in such a manner as to provide an extremely sturdy product ofiering substantially' uniform resistance to tearing or breaking stress exerted from any direction. A further object is to provide an improved reenforced product in which the reenforcing fibres are treated so as to increase their resistance o tear. A further object is to provide an adhesive for bonding the fibres to the paper, the adhesive being of such constitution that it can be assimilated with the paper boxes, strips, etc., when they are reclaimed at paper mills, thus obviating the necessity of removing the adhesive. Other specific objects and advantages will appear as the specification proceeds. I

The invention is illustrated, in one embodiment, by the accompanying drawing, in which- Fig. l is a perspective view of mechanism for applying the reenforcing fibre to the adhesive on the inner side of one of the sheets to be combined; and Fig. 2 is a broken plan view of the inner face of one of the sheets, showing the reenforcing fibres, when treated, applied to the adhesive-equipped surface of the sheet.

It has been the practice heretofore to reenforce paper strips by forming over-lapping threads in zig-zag relation on the adhesive applied to the inner face of at least one of the sheets. This product, however, has proved unsatisfactory in that it is non-uniform in its resistance to tear. Furthermore, there is a tendency for the sheet to tear along the inclined sides of the thread and, although there may be a large number of threads employed, the breaking of the threads at two or three places may permit the entire strip to be broken off. A purpose of the present invention is to provide a product which is uniformly reenforced against tear. The reenforcing threads are so applied as to cause them to run in but two directions; i. e., in a direction at right angles to the edge of the paper and in a direction parallel with the edge of the paper.

In the use of such a reenforced strip as binder tape for boxes, it is found that the strain or stress either runs lengthwise of the paper or at right angles to the sides of the paper. With the new form of tape, the threads are advantageously 55 placed to resist tear from either direction and by the avoidance of the diagonal zig-zag lines the full strength of the fibre is utilized.

In view of the well-known practice for combimng paper strips with adhesive onthe inner faces between combining rollers, it will not be necessary to give a full .description of the mechanism employed in the process. As shown more clearly in Fig. 1, sheets l0 and II are brought together, the sheet ll having previously been provided with asphalt I la, or other suitable adhesive, and after the reenforcing threads have been applied to the adhesive, the sheets are combined between rollers as in the usual practice. In the application of the reenforcing threads I2 which pass through a stationary perforated guide I3, I employ reciprocating guide bars I4, which are driven by rotating disks IE, to which drive shafts iii are eccentrically connected.

The reciprocating guide bars I4 are driven so that each thread forms relatively long horizontal lengths I! which are substantially at right angles to the edge of the paper strip, the lengths I! being spaced apart by substantially vertical loop portions l8 which, while slightly curved, are substantially parallel with the edge of the composite sheet. The several threads are also timed so as to produce an over-lapping, as shown more clearly in Fig. 2.

The threads I! may be spun or twisted, or they may be formed of single fibres, as for example, sisal, hemp, flax, etc., prepared in what is known as a knotted and tied wound-in-spool form, in continuous lengths of twenty to thirty thousand feet per pound spool. The latter type of knotted and tied fibres is relatively inexpensive and provides a sturdy reenforcing material for the composite sheets. The threads may be twisted or, if desired, they may be alternately twisted and single.

I have found that a much sturdier product can be obtained by wetting the threads or fibres l2 prior to their application to the adhesive. The threads may be passed through a water bath just before they pass through the'stationary guide l3, but I prefer to pass the threads through a bath containing water and a small amount of glycerin. The glycerin and water prevent the threads from attaching themselves throughout their length to the asphalt or other adhesive. The result is that when it is attempted to tear the product, the threads slip within the asphalt and the force of the several threads is combined against the tearing stress. Where the threads are fed in dry condition to the asphalt, they become permeated with the asphalt to form substantially one structure'and when tearing stress is exerted, it is resisted solelyby the one thread first encountered in the structure. The result is that the structure is relatively weak as com- 5 pared with the first mentioned product in which the threads tend to slip within the asphalt and to bunch in resisting the tearing stress.

Asphalt has been commonly used as the bonding material because of its flexibility, etc. The material, however, is unsatisfactory in that it makes it necessary to remove the strips before the paper boxes to which it is applied can be reclaimed in paper mills. The asphalt cannot be assimilated with the paper in the reclaiming process. Often, the cost of removing the asphalt is greater than the value of the paper reclaimed. I prefer to use in my process an adhesive which is not only flexible under various temperatures and climatic conditions but also can be assimilated in the paper reclaiming process and without requiring the removal of the binder strips. For this purpose I have found that ester-gum from starch is a satisfactory material. To give it sufficient plasticity I prefer to incorporate with it a plasticizer such as, for example, rosin residue. Other resins may be employed for this purpose. Also, it will be obvious that other suitable substitutes may be employed with an adhesive of this type. After the box has served its purpose it can be thrown as an entirety into the reclaiming vat without the necessity of making any change therein. The adhesive may disappear to some extent in the process, but to the extent that it does not disappear it is assimilated as part of the paper and without any deleterious eifect.

The reenforcedcomposite sheet is inexpensively formed, is uniformly resistant to tear, and utilizes the full strength of the threads or fibres against tea:. The resistance to tear is increased by the treating step which produces a bunching of the fibres to resist tearing stress. The entire box product can be reclaimed without requiring the removal of the binding tape.

Instead of glycerin and water, an invert-sugar solution, or other suitable water-retaining material, may be used.

The foregoing detailed description has been given for clearness of understanding only, and no unnecessary limitations should be understood therefrom, but the appended claims should be construed as broadly as permissible, in view of the prior art.

I claim:

1. The method of reenforcing paper comprising: applying adhesive between two sheets, wetting threads with glycerin and forming them between the sheets in adjacent relation and com bining the sheets by pressure.

2. The method of reenforcing paper comprising: applying adhesive between two sheets, wetting threads with glycerin and water and forming them between the sheets in adjacent relation, and combining the sheets by pressure.

FERDINAND w. HUMPHNER. 

